Nomor 39 saja mohon bantuannya

y=4y+5 + 5y+10 =180°
4y+5y =180-10-5
9y =165°
y =165:9=18,3
<D =5(18,3)+10
=101,5
x=4x+3x+5=180
7x =180-5
x 175:7=25
<B=3(25)+5
=75+5
=80°